/Engine/Source/Runtime/GeometryFramework/Public/Components/DynamicMeshComponent.h
Triangle-Vertex Tangents support. The default behavior is to use the provided external Tangents. If TangentsType == EDynamicMeshComponentTangentsMode::ExternallyProvided, the Tangent and Bitangent attributes of the FDynamicMesh3 AttributeSet are used at the SceneProxy level, the Component is not involved If TangentsType == EDynamicMeshComponentTangentsMode::AutoCalculated, the Tangents are computed internally using a fast MikkT approximation via FMeshTangentsf. They will be recomputed when the mesh is modified, however they arenotrecomputed when using the Fast Update functions above (in that caseInvalidateAutoCalculatedTangents()can be used to force recomputation) If TangentsType == EDynamicMeshComponentTangentsMode::NoTangents, the Component will not use Tangents, which will lead to incorrect rendering for any material with Normal Maps and some other shaders.
static constexpr EDynamicMeshComponentTangentsMode UseDefaultTangentsType = EDynamicMeshComponentTangentsMode::ExternallyProvided;